core

### Projected Distance for Coaxiality

PC-DMIS allows you to type a reference distance. This option in the Coaxiality dialog box (Insert | Dimension | Coaxiality) is useful when you want to specify the points along the feature axis to be used in the coaxiality calculations. When this distance is zero, the two points used will be the endpoints of the feature's axis. When this distance is nonzero, the two points used will be the starting point of the axis, and along the axis vector the distance from the starting point.

Increasing the projected distance will magnify the error. Decreasing the distance lessens the error. For example, suppose two toothpicks lay on a table, sharing the same line and touching each other at one end. At the other end of the toothpicks, about two inches apart, the error between their centerlines might be 0.005 inches. Now imagine those toothpicks are 20 inches long, they would still touch at one end and the error would be 0.005 inches at 2 inches away, but at 20 inches away from the first end, the toothpicks might have a 0.05 inch error.

The value you type in the Distance box reflects the total length of the feature.